Ok, i have worked it out! for anyone wondering (as there does not seem to be any explanation of this anywhere!) as you go round the level you want to find the vibrations in, keep pressing in time with the music (you should be doing this anyway to pick up the notes a little easier).

As you go around doing this you will occasionally feel a slight vibrating in the controller when you do it. if you can then this a vibrate spot.. sit still and keep doing it until a load of notes pop out from the ground!

Level one is the best place for this as they are very easy to find! all three are after you go down the ice slide (this should narrow it down to about ten meters of penguin travel for you)!